Page:The New International Encyclopædia 1st ed. v. 04.djvu/933

* CLASSIFICATION OF ANIMALS. 82;{ CLASSIFICATION OF ANIMALS. Classification of Vebtebratks. Fishes. — luhtliyology began as a st-ience with Arlcdi (q.v. )", who made a division into live c•las^ses, iu a useful but very artilieial manner. This con- tinued substautially uneluuiged until tlie gigan- tic labors of Cuvier resulted in a revised classi- fication, nuuh nearer nature, recognizing clearly the distinction between the fishes with bony skeletons and those with cartilaginous skeletons. Agassiz followed w ith a classification based upon the forms of the scales, the most important fea- ture of which was the recognition of the group Ganoidei. The next great generalization iu this direction of systematic arrangement was that of .1. Jliiller. who developed llie distinctness of Amphio.xus and the lampreys from other car- tilaginous fishes, and so established the new groups Cydostonii and Leptocardii ; he also pro- posed the group Dipnoi for Lcpidosiren. llux- ley's studies and new material threw new light upon the subject, and aided (Junther to form a classitication of fishes which, with oue im- portant exception, is still held by ichthyologists. For details, see Fish. Amphibia. — The Amphibia were for a long time confused with the Replilia. Thus Linnieus, 1767, who first used the term Amphibia as a group-name, included imder it: (1) Septiles pedali, including turtles (Testudo) ; Draco; Lacerta ( including crocodiles, lizards, and newts) ; and Rana. (2) Serpriitcs apodi. (3) yanles piniiati, including certain fishes. Bron- gniart. 1800. classifies reptiles as: Chelonia, .Saurii. Ophidii. and Batraehii (the last includ- ing frogs, toads, and newts). Latreille, 1804: Dum^ril, ISOli: and Oppel. 1811. while more sharply discerning the true subdivisions of am- phibians, still retain them under the head of reptiles. First, De Blainville, writing in 1816, makes Reptilia and Amphibia coordinate, but subdivisions of the 'Amphibiens:' so likewise Stannius. as late as 18.56. Latreille. 18J1, how- ever, proposes a classification which is essen- tially the same as that we now accept. Reptiles. — Reptiles were put by Linmrus under the class Amphibia, and it was not until Bron- gniart separated them that herpetology began upon a philosophic basis. It was further ad- vanced by Dumeril (1807) and Oppel (1811), who placed Cscilia with the amphibians. Cuvier and other writers did little to establish a ra- tional system within this group: and even Du- meril and Bihron, in their great Erpctolorjie qen&ale (1834.54), cling to the idea that the batrachians are only separal)le as an order from reptiles. Although De Blainville, Leuckart, and others had advocated a much deeper separation, it was not until Huxley's investigations dem- onstrated the necessity of regarding the Am- phibia and Reptilia as distinct classes that they were so set apart. See Reptile. Huxley, in his .Kniilnmy of Vertrhratcd Ani- mals (1871), divided the Vortebrata into lehthyopsiila (fishes, leptocardians, marsipo- branchs. and Amphibia), Sauropsida (birds and rei)tiles), and itammalia. Mammals and Birds. — Birds were too easily distinguished and too compact a class to have been much conffiunded with anything else, though mediaeval writers often put bats, bees, etc.. under the name. The history of their classi- fication, therefore, falls within lines agreed upon from the first, and belongs to the article Bibd. The same nuiy be said of the class Mannnalia, where the imly confusion arose from the foolish- ness of a few media'val authors, who classed buts among birds, and whales with fishes; the history of its classification will be found under Mam- malia. Oltlixe of MoDEit.v Classification. The earlier writers always classified the animal king- dom in a linear .series; usually beginning with mankind, and "descending' to the creatures deemed mo-,1 inferior. This was not with them, as it is with us, a mere matter of convenience in nuiking a list of the groups, but expressed their belief in the doctrine, imchallenged from antiquity to the lime of Lamarck and Cuvier, that there existed what they called a scala iiuliirw. They meant by that their belief that all animals could be arranged in an ascending scale of org-anization — the infusorians being suc- ceeded by polyps, these by radiated forms, these by worms, and so on to fishes, reptiles, birds, and mammals. The orders within each class, the gen- er;i within each family, conformed to the same .scale of increasing complexity; so that a linear classification, from the lower invertebrates to the highest vertebrates, was the expression of their belief in an even progress of structure. Cuvier broke into this by his arrangement of the ani- mal kingdom, into four groups, imrelated to each other — Radiata, Articulata, Mollusca, and Vertebrata — to be classified in parallel cohnnns, if at all; and this, again, has been super- seded by the conception of a form of classi- fication which sinuilates a branching tree, and tries to express a true genetic arrangement (see PnTi-OGEXY). the first attempt at which was made by Lamarck. It is, however, impracticable in the present work to attempt such an expres- sion of the classification of animals, except for restricted groups: and. in general, the linear arrangement nuist be used, bearing in mind that it is a convenient, not a scientific, expression. The classification outlined below, and fol- lowed throughout this Encyclopiedia. is that made by Profs. T. .Tefl'rcy Parker and William A. Haswell ( Text-Book of Zoology, London and New York, 1897 ). It is the most complete formu- lation of scientific conclusions, has an almost world-wide acceptance, and is generally access- ible to students and readers. These considera- tions outweigh, for the pirposes of a popular encycIo|);rdia, any objections likely to be urged against these authorities by specialists. Tlie adv:intage of taking and keeping a imiform standard of classificaticm and nomenclature throughout a work of this kind is too evident to require argument; and should there be good reason to difTer from it, here and there, these exceptions and divergences may easily be treated as they arise. In paleontologv- this scheme is supplemented by the substantially identical clas- sification of Ziltel-Kastman (Karl A. Von Zittel, Cnindziifie der I'aliiontolopie, Munich. 189,5; translated and modified by C. R. Eastman, as Text-Bool; of J'alcontoloqii, New York and Lon- don, 1900). It is needful here only to sketch the arrange- ment of the larger groups, leaving the treatment of orders, families, and lesser divisions to be given in the descriptive articles under the titles of groups, as Biiins, Fisii, Protozoa, etc.